1. Field of the Invention
The present invention relates to a wavelength-convertible light emitting device, and more particularly, to a wavelength-convertible light emitting device which allows adjustment of energy band gap of semiconductor Light Emitting Diode (LED) to vary the wavelength of emitted light in a single complete semiconductor LED.
2. Description of the Related Art
In general, semiconductor Light Emitting Diode (LED) has merits including superior monochromatic peak wavelength and light efficiency, and feasibility of miniaturization, which makes it popular as diverse light sources for display devices.
Display devices require light sources of variety of colors. However, a peculiar wavelength of light is determined in a semiconductor LED mainly by the energy band gap of the constituting material (especially, active area). Thus, in order to obtain light having a wavelength different from the peculiar one, the constituting material of the semiconductor LED needs to be changed. For example, Al and/or In can be changed to increase or decrease the energy band gap in a GaN-based semiconductor.
Alternatively, the peculiar wavelength of the LED determined by the constituting material may be converted into a desired wavelength of light with use of fluorescent material. This type of LED is manufactured by applying and hardening specific fluorescent paste on the light emission region of the LED. The wavelength of this type of LED is determined by a constant factor such as fluorescent film, which is used mainly for obtaining white light.
As described above, a single LED emits a fixed, specific wavelength light only. Therefore, in order to achieve variety of colors, a compound of different colors of LEDs, i.e., a plurality of semiconductor LEDs emitting red (R), green (G), and blue (B) have been combined and used. However, this technique not only requires a complicated driving circuit, but also is subject to inevitable loss due to mixing of colors.
Therefore, a more desirable alternative would be techniques capable of changing the wavelength of light of a single, complete product of LED, in accordance with specific conditions. But, as described above, since the wavelength of the LED is inherently determined by the energy band gap (and the characteristics of fluorescent film) of the constituting material, there has not been a disclosure of techniques for adjusting the wavelength light in a single, complete product of LED, to date.